BEHAVIOUR OF NON-CEMENTED ACETABULAR IMPLANTS LEFT IN PLACE AFTER REVISION OF THE FEMORAL COMPONENT OF TOTAL HIP ARTHROPLASTY

Abstract

Purpose: Removing a non-cemented cup can increase operative morbidity destroying bone stock. Data are thus needed concerning the long-term behaviour of non-cemented acetabular implants left in place after revision of the femoral component of a total hip arthroplasty.

Methods: We studied clinical and radiological outcome at five and fifteen years in a consecutive series of 83 patients (88 hips) with a non-cemented acetabular implant that was left in place after revision of the femoral component of a total hip arthroplasty. Mean age of the patients at revision surgery was 54 years. Two types of acetabular implants had been used: 69 titanium screen and 19 with a porocoat surface. All revisions were performed for isolated loosening of the femoral component. At revision, 33% of the patients had an osteolytic acetabulum and 52% had a bone graft.

Results: At mean follow-up of 7.5 years after revision (acetabular implants in situ for 11.6 years on the average), the mean UCLA function scores, preoperatively and at last follow-up were, respectively, pain 3.8 versus 8.9, gait 6.3 versus 8.4; function 5.8 versus 7.9; activity 4.8 versus 6.1. Six acetabular implants required a revision procedure at 7.5 years (mean, range 2 – 14 years) after the femoral revision (acetabular implants in situ for 13.3 years on the average) or acetabular loosening (n=1), conversion to a metal-on-metal bearing (n=1), and for repeated dislocation and infection (n=1). There were no hips with recurrent or worsening osteolysis.

Discussion: The duration of implantation or prior revision would not appear to be sufficient to justify removing a non-cemented acetabular implant. Presence of osteolysis does not appear to affect long-term fixation of the non-cemented acetabular implant after femoral revision. We recommend removing the acetabular screw at revision in order to correctly assess the component’s fixation.